Category A VERTICAL EMPIRE

The rocket itself had a relatively simple task to perform, which was to boost its payload as high as possible, from where the re-entry vehicles would fall with as great a velocity as possible. Some launches were completely successful in that the rocket and the experiments yielded all the data required. Sometimes the launches were successful, but the experiments failed, yielding little data. However, even when the vehicle’s performance was below optimum, the experiments could still yield good results.

Failures that would have jeopardised orbital attempts had less impact on re­entry studies. The very first flight of all, BK01, ended prematurely when the destruct system operated inadvertently. There were also problems with engine overheating leading to kerosene starvation and resultant ‘cold thrusting’, particularly in the second (BK03) and fourth flights (BK05), but again, these were solved relatively early in the programme. ‘Cold thrusting’ occurs when the engine consumes HTP in the absence of kerosene: decomposition still takes place, but the thrust is very sharply reduced. In addition, on many flights the kerosene was exhausted before the HTP, resulting in a few seconds of cold thrust after ‘all burnt’. The discrepancy between the calibration during test firing and the actual launch was never pinned down.

The first stage of the vehicle performed exactly as intended on 15 of the 22 Black Knight flights. Other launches had problems in one way or another:

BK01: the self-destruct mechanism was accidentally triggered near the end of the flight.

BK03 and BK05: overheating in the engine bay lead to a fuel lock in the kerosene pipes, resulting in a long period of cold thrusting.

BK07: one chamber reverted to cold thrust after 100 seconds. Over 80% nominal velocity achieved.

BK14: pipe failure caused loss of kerosene: cold thrusting after 130 seconds. 85% nominal velocity achieved.

BK12: 6.8% difference in mixture ratio between flight and calibration.

BK23: premature shut down of engine due to gearbox failure 3 seconds before expected flame out.

Of the 22 flights listed, seven would not have made it into orbit if they had been satellite launch vehicles. Most of these problems could be considered as developmental difficulties that occur with any new technology. As a very first attempt at a modern liquid fuel ballistic vehicle, this is a fairly good record, with no major failures at all. It is also a tribute to the engineers at Saunders Roe and at Armstrong Siddeley Motors.

However, Black Knight was a success in a different direction. It gave RAE the confidence in the basic design, and as a consequence, many further projects were proposed using Black Knight as a basis. One, of course, was the Black Prince launcher and its various derivatives discussed in the BSSLV chapter. Another was Black Arrow – the subject of the next chapter.

The paper that follows is the Air Staff description of the prototype Blue Streak underground launcher. The prototype was known as K11.

A drawing showing a full reconstruction of the launcher can be found in Chapter 6 (Figure 50).

K.11 prototype underground emplacement

(1) The potential attacker is believed to have the capability to produce an explosion of 1 megaton yield on the ground or in the air with an accuracy of xh nautical mile from his target. The launcher must be able to withstand such an explosion and successfully fire its own missile without outside assistance within 24 hours.

(2) The emplacement must be able to fire the missile in all weathers.

(3) The emplacement must contain the missile and the necessary facilities for operating and servicing it and for messing and accommodating the concerned personnel. Since an alert may be sounded when the outgoing shift is handing over to the incoming shift, messing facilities must be adequate for two shifts.

(4) Storage space for the missile propellant fuels, food and other stores and equipment must be provided.

(5) Adequate ventilation including the efficient and speedy expulsion of missile exhaust after firing, must be provided together with facilities for conditioning, purifying and circulating air.

(6) Insulation against the electro-magnetic effects associated with a nuclear explosion.

(7) The emplacement must be self-contained for an emergency period of four days (covering three days before an attack is expected and one day afterwards).

II. SITE CRITERIA

1. Rock mass (hard chalk, limestone or better) not less than 300 ft thick and preferably with no overburden. But if overburden is present, it must be soft and not more than 25 ft thick.

2. Easy and firm access from main road to emplacement for transport of missile, equipment and stores.

3. Ease of guarding.

4. Neighbouring inhabited property must be more than 3,000 feet from the emplacement (this may be reduced as experience is gained in K.11).

III. DESIGN OF EMPLACEMENT

1. Basically, the emplacement consists of a hollow re-inforced concrete cylinder, 66 feet internal diameter, extending downwards from ground level to a depth of 134 feet and divided internally into two main sections by a vertical concrete wall. One section houses a U-shaped tube, the arms of which are separated by a concrete wall and are, respectively, the missile shaft and its efflux duct. The surface apertures of this U-tube are covered by a lid which can move horizontally on guide tracks. The other main section within the cylinder is divided into seven compartments, each with concrete floor and ceiling, for the various storage, operating, technical and domestic functions.

2. The internal diameter (66 feet) of the concrete cylinder is determined solely by what is to be accommodated. Protection against an explosion as… above is given by the lid and by the re-inforced concrete roof walls and foundations. The wall thickness will depend on the geological characteristics of the surrounding rock and may well be of the order of 6 feet. The depth of 134 feet is arrived at primarily to give sufficient clearance below the missile (itself 79 feet long) to allow for de-fuelling and re-fuelling the missile into and from the liquid oxygen and kerosene storage tanks located on the 7th floor.

3. A nuclear explosion produces certain electro-magnetic effects which could gravely injure the electronic systems built into the missile and on which its efficient functioning depends. To screen the emplacement from these effects the concrete cylinder will be wholly encased in W thick mild steel plate.

Missile shaft

4. The shaft is octagonal in section, 25 feet across and has an acoustic lining. The octagonal shape, which has been proved by tests, will facilitate the mounting of the acoustic lining and of the four hinged platforms which are spaced at intervals down the shaft.

5. The purpose of the acoustic lining is to prevent damage to the missile from the extremely high noise level produced by the main thrust chambers in the confines of the missile shaft.

6. The missile rests vertically in the shaft on a launcher supported by four suspension limbs attached to the wall of the shaft.

7. Access to the shaft for servicing purposes is through blast-proof doors opening on to the second and sixth floor.

Efflux duct

8. This has an area approximately 60% of that of the missile shaft and in section is half-octagonal in shape. This gives symmetry in the structure and at the surface aperture. A series of deflector plates at the exit will take the exhaust gases away from the missile as it leaves its own shaft.

Storage, Operating, Technical and Domestic Section.

9. This is divided into seven floors, as below, connected by a lift and staircase running from the first floor (at the top) down to the sixth floor:

First Floor

This floor contains:

(a) lid operating mechanism

(b) generating equipment

(c) air conditioning equipment

(d) blast valves for all intakes and exhaust ducts.

All this equipment has been centred as far as possible on this floor to avoid large air trunking systems being provided throughout the site. In the event of contaminated air being taken in, arrangements will be made to close off this floor (other than the general access facilities) thus allowing the generating and air conditioning plant to continue to operate without risk of contamination of the rest of the site.

Second Floor

This floor contains:

(a) Upper storage and maintenance area for the missile, together with two magazine type stores for the payload and the pyrotechnic equipment of the missile, i. e. retro rockets, head propulsion rockets, etc.

(b) Certain items of heating and ventilating equipment for which space is not available on the first floor.

(c) The refrigeration supply for the missile guidance equipment

(d) Blast proof access doors to the upper portion of the missile shaft.

Third Floor

This floor contains:

(a) Auto-collimator equipment

(b) Radio and communications equipment

(c) Site and missile control and checkout equipment

(d) Azimuth bearing and general purpose telescopes.

This floor level is controlled by the relationship required between the auto­collimator and the inertial guidance unit in the missile.

Fourth Floor

This floor contains all the general domestic accommodation including kitchen, recreation and sleeping facilities, etc., together with a small battery room and a switch room.

Fifth Floor

This is intended as the main storage area for the site generally. It also contains one or two tanks which it is not practical to put in the tank room on the seventh floor.

Sixth Floor

This floor is the lower maintenance area and contains the blast proof access door to the lower portion of the weapon shaft. Small hydraulic units are installed on this floor to supply the auto-pilot and launcher services. A small mono rail is provided that can be extended into the missile shaft for maintenance purposes. Access is also provided into the lox and kerosene [‘and water systems’ crossed out in original and ‘rooms on the seventh floor’ handwritten in]

Seventh Floor

This floor is divided in two by a structural wall to separate the liquid oxygen and nitrogen systems from the kerosene and water systems.

The Lox room contains:

(a) Main Lox storage tank

(b) Main liquid nitrogen tank

(c) High pressure gaseous nitrogen storage bottles

(d) The Lox start tank

(e) Liquid oxygen topping up pump

Subsidiary rooms contain:

(a) Liquid oxygen recondensing units

(b) Liquid nitrogen recondensing unit

(c) Liquid nitrogen topping up pump

(d) Liquid nitrogen evaporating plant

The kerosene room contains:

(a) The main kerosene storage tank

(b) The main water storage tank

(c) The kerosene recirculating pump

(d) The kerosene start tank

The access doors from the sixth floor will normally be kept closed and ventilation shafts are provided from these two rooms through the main structure to the surface pipe systems are also provided in these vent shafts for filling these systems from the surface,

IV. DESIGN OF LID

1. The detailed design of the lid is about to form the subject of a special design study by selected firms.

2. The purpose of the lid is to protect the missile from the effects of attack and to remain fully serviceable itself after such attack. Since the missile is completely unprotected when the lid is open, the time allowed immediately prior to firing the missile for opening the lid must be kept to a minimum and has been put at 17 seconds.

V. DESIGN OF SITE

1. The main requirement is to achieve maximum security and this calls for both the site and its immediate surrounds to be enclosed by a security fence and to be clear of obstructions to visions. The cleared area extends also beyond the site perimeter. The need to camouflage the site is at present being considered. A simple road system with associated hardstandings must be provided within the site.

2. The site will be about 3 acres in extent.

3. The site includes the main entrance to the emplacement, consisting of three flights of steps, protected only against weather and leading down to a cylindrical air lock giving access to the first floor of the emplacement.

The design and production of aircraft became the concern of the Ministry of Aircraft Production in May 1940. In April 1946 the Ministry of Aircraft Production was dissolved and its powers transferred to the Ministry of Supply, whose primary duty was the furnishing of supplies and the carrying out of research design and development for the services.

Firstly, this lead to problems in that the Ministry of Supply was responsible for developing aircraft, but at the same time, it would not be the end user, and thus lacked the incentive to overcome obstacles, and to speed the process along. Secondly, it did not have to operate the obsolescent material that the prototypes would replace, and so here too lacked that final sense of urgency. A third criticism was its industrial policy: projects were often not allocated to firms on the basis of their ability to carry them out, but often given to firms who were short of work in order to keep them busy. Sometimes the rationale behind some of the decisions was hard to fathom. Blue Steel was given to Avro, who had no experience whatsoever in guided weapons and had to set up a division from scratch – a process which must have cost a year or so of development time.

Reginald Maudling was Minister of Supply from 1955 to 1957. He has this to say about the Ministry in his autobiography:

When Anthony Eden became Prime Minister in 1955, he promoted me to Minister of Supply, which was my first full Ministerial post… It was a strange Department, and the target of a good deal of criticism, much of it justified. It was supposed to be concerned mainly with the supply of munitions to the three Services, and this was a large part of the routine work of the Department, but in addition it had responsibility for the aircraft production industry generally. The Government exercised a great deal of influence over the industry because, with the scale of modern projects and the vast amount of research expenditure involved, the industry had to rely heavily on the Government for contracts and for support. In addition, the Ministry of Supply was responsible for the Royal Aircraft Establishment at Farnborough, a quite remarkable institution, upon which industry relied heavily for scientific and technical support.

Inevitably we got caught in the middle in all disputes that went on between manufacturer and consumer. This was particularly true in the field of military aircraft, with the Air Force always demanding more from the manufacturers and complaining they were not getting their requirements met, while the manufacturers were saying that they were doing all that was possible and the RAF were asking too much. Relations between the Ministry of Supply and the Air Ministry were not ideal, and indeed I had from time to time considerable battles with Nigel Birch, who was then Secretary of State for Air. I came to the conclusion during the time I was there that the system was a bad one and that the interposition of a third party between customer and supplier, rather than acting as a pacifying agent, merely exacerbated argument. I did, in fact, recommend the abolition of the Ministry of Supply and when Harold Macmillan asked me to continue in that job when he became Prime Minister I naturally refused, because it seemed absurd to continue as Minister in charge of a Department whose existence I did not think was justified.1

Sir Frank Cooper, one of the senior Civil Servants of the time (among many other posts, Permanent Secretary at the Ministry of Defence from 1976 until 1982), had this to say about the Ministry of Supply in the context of the TSR 2, although his strictures could be applied more generally:

There was no doubt that relations with the Ministry of Aviation /Supply and the Air Ministry went from bad to worse and that these poor relations spread increasingly to the Ministry of Defence as a whole. The breach itself was of long-standing. The basic cause was lack of trust, particularly as regards the information received by the Air Ministry. The trust was lacking because the Procurement Ministry stood between the Air Ministry as the customer, and industry as the supplier. Moreover nothing seemed to arrive at the right time and at the right price, let alone with the desired performance. The lack of trust was exacerbated by the financial arrangements under which the Ministry of Supply/Aviation recovered production costs from the Air Ministry but was left with the research and development costs. Hence, there was no clear objective against which the supply department could assess performance and value.

An Overview

In 1945 the RAF and USAF had the world’s most powerful strategic bomber fleets, yet they were on the point of becoming obsolete, and the factor that was driving them obsolete was the jet fighter. The increase in performance that the jet engine gave to interceptors rendered the likes of the Lancaster and its derivatives hopelessly vulnerable. If airborne radar and guided weapons are added to the armoury of the fighter, the balance tilts even further away from the bomber.

One answer, of course, was to build jet powered bombers. The Air Ministry had been aware of this for some time, and before the Second World War had ended, had issued the Operational Requirements that would lead eventually to the V bombers, which were, together with guided missiles and the development of atomic weapons, a major part of the post-war defence programme. Similarly, the Americans, while having pushed their propeller driven designs as far as feasible, were also busy designing jet bombers in the 1940s and 1950s, culminating in the B52, still in service.

In post-war Europe, the strategic focus for the Western Allies switched very rapidly from Germany to Soviet Russia. The Soviet Air Force was also a formidable fighting machine, although it had evolved along lines more tactical than strategic. It had, on the drawing board, some impressive interceptor aircraft such as the MiG 15.

The first rocket powered interceptor of all was the German Me 163, which was used in the latter stages of the war against the high-flying daylight bombing raids by American B17s. It was small and simple, using a wheeled trolley for take-off and a skid for landing. Its endurance was extremely limited, but it had, by the standards of the time, a phenomenal rate of climb. However, despite its impressive performance, it had very few ‘kills’ credited to it – one source gives a total of nine.1

But the Me 163 obviously impressed the British Air Staff, and proposals for a very similar aircraft began to emerge in the late 1940s. The designs being considered were for a very similar aircraft: a rocket motor with no other means of propulsion, a simple skid for a dead stick (i. e., unpowered) landing, and a battery of unguided 0.5 inch rockets. It was intended for point defence, for airfields and the like. With its limited endurance, it was not suitable for much else. Such an aircraft would have been able to carry enough fuel for only three or four minutes powered flight. In effect, it was almost a manned guided missile, and the unpowered landing technique would not have made it popular with pilots.

In 1945, the whole strategic equation had been rewritten with the advent of the atomic bomb. There was no great urgency for the rocket interceptor in the immediate war years, since the Russians had built a formidable tactical air force, but had almost nothing in the way of heavy bombers. In addition, at that time it was thought that the Russians would not have atomic weapons until the mid – 1950s. In the event, the first Russian fission bomb was exploded in 1949.

A further difficulty to the problem of interception was that any jet atomic bomber would be flying very high, very fast. Up until the 1960s, the bomber’s best defence had always been height. The higher the aircraft, the more difficult it is to detect, the more difficult it is to hit with conventional anti-aircraft shells, and the more difficult it is to intercept. For interceptor fighters, the choice was either to loiter at high altitudes, which, given their limited endurance, was not usually a feasible option, or to reach these heights as quickly as possible. In the 1940s, the performance of the jet engine was not sufficient to do this. The problem was to get an interceptor to that height quickly enough and with a sufficient speed differential to be able to manoeuvre into a position in order to be able to attack. It was further realised that such an attack would probably be made by guided weapons of some form – either heat seeking, using infra-red sensors, or radar controlled.

There was a fundamental problem with an aircraft as small as the proposed rocket interceptor, in that it would have been able to fly only in daylight and reasonably good weather, and this problem would plague all the designs until the later P177 and F155 designs. It is curious, given these limitations, that there was so much interest in the design. When Churchill was returned to government in 1951, he took a personal interest in the project, asking Lindemann, his scientific advisor and iminence grise, to look further into the idea. But the RAF strategic offensive had been entirely night based, and the RAF had rarely encountered the Me 163, and knew of it mainly by reputation. Similarly the German offensive against the UK had been mainly night-based after the early attacks in 1940. It was only the Americans, with high-flying well-armed Flying Fortresses who attacked during the day. So why were the RAF so interested in a fighter that could be used only in daylight? One answer, of course, is the defence of the airfields where the V bombers would be based – effectively point defence.

But despite this, the Air Ministry issued OR 301. The main points of the designs requested were that they should be relatively simple and would use rockets for the main propulsion. However, quick calculations would show that the endurance of such an aircraft is extremely limited. Let us do some order of magnitude calculations.

Given a rocket motor with an S. I. of 200 seconds and mean thrust of 4,000 lb (the Spectre was rated at up to 8,000 lb thrust, but could be throttled) then the fuel consumption is around 20 lb per second. Given that the aircraft might carry

6,0 lb of fuel, this gives a powered flight time of 300 seconds or 5 minutes! This is not long in which to take off, intercept and shoot down an incoming aircraft at an altitude of almost 10 miles.

There are other problems too: high-speed, supersonic aircraft make very poor gliders! If the pilot’s interception takes him too far from his base, then he will be forced to eject. Similarly, every landing will have to be one chance only. Landing such an aircraft unpowered would be a pilot’s nightmare. It soon became obvious that an auxiliary turbojet would have to be fitted. This extended the post­interception phase and enabled the pilot to ‘go round again’ if there was a problem on landing.

But there can be other criticisms of the basic concept. The OR stated ‘in order to facilitate ease and speed of production, the aircraft and its equipment are to be as simple as possible.’ This, however, was a mistake. Although it is very tempting to go for a simple design on these grounds, any such design would have some fatal flaws. The first is that there was no inbuilt air-to-air radar, which would have been no novelty in 1952, and the lack of it would be a severe handicap for high-flying interceptor aircraft. It can also be argued that, owing to the limited nature of the OR, obsolescence was inevitable. The aircraft would be restricted to ground control and daylight interception. Would ground control be readily available in a nuclear war scenario?

Again, to quote from the OR:

Current day interceptor projects are expected to be adequate in performance to match the enemy threat in normal circumstances, but may be unable to destroy enemy aircraft carrying out special operations at exceptional heights.

An aircraft to fulfil this requirement must have an outstanding ceiling and altitude performance. So far as is known at present, the characteristics can only be provided by rocket propulsion, and, although aware of the probable operating limitations of this method, the Air Staff consider that the promise of tactical advantage more than outweighs other considerations.

It is surprising in other ways that the OR was put in this way. As mentioned, Bomber Command throughout the Second World War carried out the vast majority of its raids at night. It is unlikely that the Russians would attack by day, knowing how vulnerable such an operation would be with the advance warning that would be given as the bombers crossed the width of Europe. So OR 301 was in danger of becoming a requirement for an interceptor without a target.

But another key phrase is, of course, ‘special operations at high altitudes’. This was an oblique way of referring to the nuclear armed bomber, and there is one crucial difference between a conventional and a nuclear bomber. With conventional bombing, it is accepted that most of the bombers will get through the defences. Indeed, during the Bomber Command offensive, the German defences would be congratulating themselves if they inflicted 10% losses on a night’s raid. In nuclear terms, this is completely reversed. Even 90% losses on a bomber fleet could mean devastation wreaked by the remaining 10%. This was the philosophy behind the rocket interceptor.

In any event, designs were sought from all the major aircraft firms – Blackburn, Westland, Fairey Aviation, Saunders Roe and Bristol, among others. Saunders Roe were not originally on the list, and given their previous work, this is not surprising. However, they had gained experience of modern aircraft with the SRA1, a jet-propelled flying boat fighter. Bizarre though this concept might seem (it was intended for the Pacific war against Japan), it had two axial flow turbo jets, and, given the limitations on the design posed by its aquatic role, had a very respectable performance.

These designs were passed through to RAE to ‘score’ them on a complicated points system. The two that fared best were the Saunders Roe P154 and the Avro 720. The basic difference between the Avro design and the others is that Avro chose liquid oxygen and kerosene as fuels, as opposed to HTP/kerosene. The Gamma and the de Havilland Spectre rocket motors were the HTP choices. HTP was undoubtedly safer in a crash, although any rocket aircraft was inherently dangerous, owing to the explosive nature of fuel and oxidant.

But the limitations of these designs became obvious. Saunders Roe then came up with the suggestion that the aircraft should carry an auxiliary jet engine and have proper landing gear. The point of the jet was to supplement the rocket, and then to provide a limited cruise facility, followed by a return to base. The jet engine was of relatively low thrust compared with the rocket, but had high endurance. The Spectre was of 8,000 lb thrust; the Viper jet engine of 1,850 lb. This suggestion was also under consideration by the Ministry, and so Saunders Roe produced modified designs. The SR53 design then emerged from the various proposals.

Avro and Saunders Roe were instructed to build three prototypes each, before the first of many defence economy axes fell. The projects were put on hold. Eventually the Avro prototype, though nearly complete, was to be dropped. Saunders Roe was asked to build two prototypes of the F138D/SR53 (the first designation was the Ministry code for the project, the second was Saunders Roe’s).

Saunders Roe pressed on with further designs since the SR53 was felt to be too limited. Saunders Roe proposed the P177, with a much more powerful jet engine, and limited Air Interception capabilities, in other words, a radar set mounted in the nose. Both the RAF and Navy were impressed with this design, and for once, the two Services were in full agreement over a project. The P177 was given the go-ahead and Saunders Roe were asked to produce an initial 27 aircrafts. The two prototype SR53s were proceeded with so as to give experience with the concept.

The Air Staff went further and issued another requirement for a rocket assisted interceptor, F155, with an even more demanding specification. A number of proposals were put forward, with the ‘winner’ being a development of the Fairey Delta.

A variety of factors led to the cancellations of the P177 and the F155. The main reason, although not the commonly accepted reason, was a change in defence policy. At that time, the decisions about future defence projects and related policy were taken on the basis of reports by the DRPC, the current chairman being Sir Frederick Brundrett. The work that had been done over the past ten years on guided weapons, or surface to air missiles, was reaching fruition in the form of the Bloodhound missile.

Bloodhound was a remarkably successful missile, with a range of over 50 miles, being deployed in British service between 1958 and 1991. It was also deployed by Australia, Singapore, Sweden and Switzerland. Not only could it do the same job as the rocket assisted interceptors, it could do it a good deal cheaper. It costs a good deal less to maintain a squadron of missiles sitting on an airfield for ten years than it does to maintain and fly an equivalent squadron of manned aircraft.

There was also another reason for dropping the rocket assisted fighter: conventional jets with afterburners gave a performance not far short of the rocket. The English Electric P1, which went into the service as the Lightning, had a performance nearly as good as the P177. It too suffered from endurance problems!

Almost coincidental with this change of policy came a change of Prime Minister, when Eden resigned to be replaced by Macmillan. Macmillan wanted defence economies, and with that in mind, appointed Sandys as Minister of Defence. Very soon after the appointment came the 1957 Defence White Paper; indeed, so soon that most of the policy must have been established prior to Sandys. The 1957 White Paper became famous for three points: the abolition of National Service, considerable cuts in Defence spending, and cancellation of various aircraft projects in favour of missiles. On closer examination it is difficult to see how many other projects other than the rocket interceptors were cancelled, but it produced a considerable psychological shock to the British aircraft industry. There was a strong sense that there would be ‘no more manned aircraft’ for the RAF.

So despite a bitter rear-guard struggle fought by the Minister of Supply, Aubrey Jones, the P177 was cancelled. The Admiralty in particular pressed Sandys hard, and forced him eventually to admit that although the Navy still needed the aircraft for its carriers, the Defence Budget could not afford it. Both Saunders Roe and the Ministry of Supply tried hard to sell the aircraft overseas: there was Luftwaffe interest, and Saunders Roe prepared brochures for the Australian and Swedish Governments. However, Brundrett was against even this idea, arguing that we were trying to sell an aircraft which was obsolete, and that the Germans would be better off buying missiles from the UK. At the end of 1957, the Germans decided not to buy the aircraft; instead, they bought the Lockheed F-104 Starfighter, which became notorious in later years for its accident rate. Lockheed also had rather persuasive selling tactics unlikely to be matched by a small firm on the Isle of Wight!

The Lightning interceptor remained after the 1957 White Paper: later marks had almost the same capability as the P177 (and the same weakness in terms of endurance). It also showed the usefulness of a manned aircraft in the many interceptions carried out along the north and east coasts of the UK against long – range Russian aircraft probing British air defences.

Both the Lightning and the P177 fitted the specification for which they were designed more than adequately: the problem was not with the aircraft but with the specification and the changes in both technology and policy as the Ministry of Supply lumbered through its slow development procedures.

The apotheosis of the concept of the rocket interceptor was a design submitted by Saunders Roe for the Air Staff requirement F155. Saunders Roe’s design brochure was very impressive, leading to a behemoth of an aircraft with two jet engines with reheat and four rocket motors. This was an interceptor capable of taking on anything. It was also immensely huge, rivalling in scale even the TSR 2. Indeed, its size was to be its downfall. The original specification had been for an aircraft to carry two infra-red guided missiles and two radar guided missiles. Issue 2 specified one type or the other, with an option to switch. But whereas the other firms submitted their modified design, Saunders Roe stuck to their leviathan, and it was promptly discarded by the Ministry on grounds of size and expense. Fairey and Armstrong Whitworth were the chief contenders, with machines half the size, but again the project was never completed, falling foul of the same change in defence policy.

So the end result of all the work was the two flying prototypes of the SR53, and these were never to be anything other than research machines. But more than anything else, the concept had proved fatally susceptible to ‘mission creep’ over a period of ten years, from an extremely simple, almost crude, initial concept, to a highly sophisticated final series of designs. There is a saying, attributed to Voltaire, that the best is the enemy of the good (‘Le mieux est l’ennemi du bien’). If the RAF had wanted a good point defence high-flying interceptor, it could have had such a machine with 50 or so SR53s by the late 1950s. The concept of the rocket interceptor never had a chance to prove itself, partly because the window of opportunity in the technologies available was relatively narrow. This window was never fully utilised by the often slow progress of Operational Requirements through the Air Ministry, Ministry of Supply, the budget limitations and the desire to go one better as each design became finalised.

Rocket motors did have their drawbacks in the form of relatively limited operating time and use of exotic and expensive fuels. Handling such fuel would have produced difficulties when servicing the aircraft, and even though HTP is reckoned to be relatively benign as far as rocket fuels go, it is still hazardous to handle.

The other factors leading to cancellations were the enforced defence economies, the constant improvement in jet engines, and the development of guided weapons. The role of interception was to be taken by the Lightning aircraft, which although it too had an impressive rate of climb to altitude, was also limited by range, at least, in the earlier marks. But it was the advent of guided missiles, principally Bloodhound, deployed along the East Coast V bomber bases and at RAF bases elsewhere, which finally killed off the rocket interceptors.

However, one further major question is left unanswered. The motives of the Services, the Ministry of Aviation, the Air Ministry and the Treasury appear obvious enough. What is not obvious is why the Ministry of Defence and Powell himself took the position they did.

There are several possible scenarios.

The first is that Powell himself, possibly in concert with other senior civil servants in other departments, felt that the project was insupportable. Although he did not have the authority himself to cancel it, he could set up circumstances that gave others the opportunity. Thus if the Treasury and the Chiefs of Staff were to object sufficiently, then the new and relatively inexperienced Minister, fresh to the Cabinet, had little choice. It is interesting that the major attack on the project was only mounted after the October 1959 election, when Sandys was moved from Defence to Aviation. It would also mean keeping the details of the report from Sandys at the Aviation ministry for as long as possible, which seems to have been the case.

Another possibility lies not with Powell but with Watkinson and Macmillan, as indicated in the Daily Mail article. Under this scenario, Watkinson is appointed by Macmillan with a specific brief to ensure the cancellation. But why would Macmillan want to do this?

A possible answer lies not in the cost, but the timing of the cost. Expenditure on Blue Streak would reach its peak from 1960 to 1965. Although expensive in terms of capital cost, its running costs were (or appeared to be) extremely low. Both Skybolt and Polaris were considerably less expensive to buy (the development costs would have been covered by the Americans) but their running costs were very much higher. Flying aircraft, or running submarines, does not come cheap. However, these running costs would not have been incurred for several years to come, which would be well beyond the lifetime of the Macmillan Government.

A further answer might lie in the silos themselves. It is curious that the estimates of the vulnerability of the silos were never questioned one way or the other. Although the Air Ministry and the Ministry of Supply had done the calculations as best they could, the design was still a paper one (indeed, the design of the lid, one of the most crucial points in any silo design, had not been finalised by the time of the cancellation). In a sense, this makes a nonsense of the whole argument: since no one actually knew the exact strength of the silos, the debate was in many ways so much hot air. But they would raise political difficulties. They would certainly consume a great deal of civil engineering resources, and the political impact of such large and controversial structures in Conservative constituencies should not be overlooked. Indeed, the Home Office under Butler had come into the argument at one stage, requesting that the silos be situated on the east side of the country so that, given prevailing westerly winds, fallout from an attack would to taken away from the UK. In addition, for Civil Defence purposes, Butler wanted the sites well away from centres of population.

But however well-disguised the real reasons were, and no matter how much the papers conceal the true motives, a very revealing letter was written a year after the cancellation. A Technical Sub-Committee was to be set up for the BND(SG), and Zuckerman wrote to various eminent scientists, inviting them to join. One was Sir Robert Cockburn, who had been working for the Government in various capacities since the war, and at one time had been CGWL at the Ministry of Aviation. He wrote back to Zuckerman, and one paragraph of his letter reads:

Blue Streak was cancelled because it was not politically viable rather than because it could be pre-empted. The scale of pre-emption was admitted to be of the order of

3,0 megatons. Supporters of the system argued that this was so excessive that pre­emption could be ignored in practice. The argument was not accepted and vulnerability was advanced as the main reason for cancellation. The real reasons were more fundamental although still not clearly appreciated. I suggest no British
statesman could visualise exploiting a deterrent threat which if mishandled could only lead to the annihilation of the whole country; nor could he believe that a threat involving such consequences would be taken seriously by an opponent.25

In other words, once missiles are fired, they cannot be recalled. And with missiles, which are seen as potentially vulnerable whilst on the ground, the incentive is to fire early. Bombers can be recalled, and they do not need to fire off their missiles until it is certain the UK has been attacked. The same is true of submarines lying undetected in the Atlantic. This, probably more than anything else, reflected the true reason why Blue Streak was cancelled.

The cancellation is a graphic example of how Whitehall can work. What is of more interest is the study of how much policy was made by officials and how much by Ministers. Ministers rely on officials for advice: how impartial was that advice? Civil servants themselves have opinions. Furthermore, the documentary evidence that survives tends to suggest that a good deal of policy was not made on paper, but in briefings, and that papers were presented with a particular pre­determined slant or viewpoint (although there is nothing new in that!). Ultimately, it might be said that the correct decision was made, but that the evidence presented was misleading, and the motivations of the various participants were, to say the least, often concealed.

Two stage. Launched 24 May 1960 at 21:00. Apogee 350 miles.

BK08, the first two-stage vehicle to be fired, was intended to obtain re-entry of the head at a higher speed. Main stage performance was good, but the second stage did not separate from the main stage and so was not ignited. The failure of explosive bolts or inertia switch circuitry was the probable cause. The trial, however, proved the aerodynamics of a new configuration, the control stability with the heavier vehicle, the stressing with greatly increased forward weight and the necessarily modified guidance arrangements.

Certainly the individual vehicles were cheap enough. A letter from Saunders Roe to the Ministry of Aviation in October 1958 has this to say:

In answer to the enquiry you made concerning the cost of additional Black Knight rounds, I quote below a Memorandum from our Commercial Manager which I hope provides you with the information you wanted:-

The approximate cost of the production of the vehicle is £41,000 as it leaves our factory at East Cowes. This figure includes the Armstrong Siddeley engine at a cost

of £15,000 each but excludes the cost of items of normal Embodiment Loan Equipment.

In addition there is the cost of testing and setting up the vehicle at High Down and later in Australia. As you will appreciate this is a very difficult figure to assess but I would suggest it is about £7,000 per vehicle. It is possible that this would be reduced if series production was underway but it would appear that we shall be constantly modifying each individual Equipment in the next year or two, and £7,000, therefore, would be a fairly safe figure to use.7

To modern eyes, these figures are astonishing. The idea that the Gamma 201 rocket motor cost only £15,000 tells us a great deal about inflation between then and now – but also that Black Knight was not exactly overpriced. This contrasts with a Treasury memo of January 1961, talking about Black Knight.

The memo begins with some general comments, which show some misconceptions: ‘In 1956, we agreed to the expenditure of £5m., for which it was expected to get 12 firings a year… ’ The mistake seems to lie with the Treasury – there was never any suggestion of 12 firings a year. The memo then goes on to say, ‘The first ten firings will work out at a cost of about £%m. each!’ There is a certain note of incredulity in the author’s tone, which makes one wonder what sum of money the Treasury would think reasonable for a programme in which the re-entry heads are shot 500 miles out into space. The total expenditure of the programme to date had been around £6 million, and the Ministry of Aviation were now asking for more funds. The author goes on to say:

On balance I think I recommend approval of this proposal – just. Any doubts I have are stilled by one further consideration which may appear cowardly but is, I believe, realistic: I do not think we have any hope at the present moment of killing the Black Knight series of experiments: and even if we had, to persuade Ministers to do so now would ruin our chances of killing the Blue Streak launcher project, for we could not hope to persuade Ministers to face the political odium of two further cancellations close together. Black Knight, although pretty expensive (and I would expect the C.&A. G.* at some time to get on to it) is at least working successfully. It has had a good press. It provides a useful vehicle for a certain amount of incidental upper atmosphere research of the kind Universities can share in. Its cancellation would be very strongly opposed in the Ministry, would draw a great deal of adverse criticism in public-after all, we have now got over the most expensive early stages – and would only save less than £1m. a year. Far better, I think, to keep our sights on the larger fish, Blue Streak, than to spoil Ministerial appetites with this smaller fry.8 [*C.&A. G.: Comptroller and Auditor General – part of the National Audit Office]

The author is proposing that the Treasury should let the Black Knight programme carry on simply because it gives it a greater chance to cancel Blue

Streak. For cynicism and superciliousness (‘a certain amount of incidental upper atmosphere research… ’) this is difficult to beat.

The author noted that since the next series of flights were to be done in co-operation with the Americans, it would be difficult to reduce the programme further. After all, ‘Given that we indulge in this hobby at all, co-operation with the US is surely sensible and desirable’9.

One of the functions of the Treasury is to keep a close eye on government expenditure: it does help if they get their facts right, and are rather more careful when it comes to making comment on technical matters which are somewhat beyond their grasp. [15]

The document below is the full text of the note written by Sir Steuart Mitchell, CGWL, to the Minister of Aviation, Peter Thorneycroft, concerning the possibility of using Spadeadam to launch Blue Streak.

The following are hastily prepared views on the above.

Technically

Spadeadam certainly would be feasible, and in nearly every way technically would be better than anywhere else.

2. Costwise. (Capitol plus operating) Spadeadam would be as cheap as Woomera, and cheaper than anywhere else.

3. Method

Trajectory about north 35 east.

Overflies Kelso. Crosses coast ever Eyemouth.

Passes 25 miles east of Aberdeen, and 100 miles west of the Norwegian coast.

Down range station, very well placed, would be in Spitsbergen (Norway, open all year round). Alternative would be at Tromso, which is possible but not so well placed.

First stage impact 200 miles off Norwegian coast abreast Namsos. (This is west of the Narvik – North Sea ore traffic lane).

Second stage impact on the polar ice cap.

4. Risks

Quick and Rough estimates are:-

1. The chance of having to cut down the missile on to UK territory beyond the Spadeadam Range Area is approximately:-

/% to 2% during the development period.

2. The chance of a missile having to be cut down and then landing in a “populated area” is approximately :-

1/50% to 1/5% during the development period

3. The chance of killing a person is approximately 1 in 10,000 per round fired in the development phase.

4. The risk to Norwegian territory is negligible.

5. The risk to shipping, is negligible.

5. Nature of the Risk

The cut-down risk is numerically greatest within the first mile. The Spadeadam Range area extends to just over a mile from the launch.

A missile cut down within five miles would have a considerable fire risk from fuel and oxidant. Outside five miles a cut-down missile is primarily a fragment risk not a fuel oxidant risk.

6. Comparison with Aircraft Risks

Aircraft crashes over the last 5 years in the UK average about 90 per annum. The probable total damage to lives and property of persons on the ground per annum from firings from Spadeadam is estimated to be about 1/10 of that from aircraft crashes in the UK per annum.

One Boeing 707 crashing near take off from London airport with full tanks and 128 passengers, or two Boeings colliding over London, would be far more serious than any conceivable accident with a space launcher.

7. Black Knight experience

None of the total of eleven firings so far done with Black Knight would have landed in UK territory if they had been fired from Spadeadam.

8. Conclusion

Spadeadam is technically both feasible and attractive. From the cost point of view, it is approximately the same as Woomera, and is much cheaper than any alternative.

It must be accepted, however, that some cut-downs on to UK territory would inevitably occur if we fire from Spadeadam. The chance of serious damage to life and property from such cut-downs are numerically small.

The risk of damage to foreign countries, or to shipping, is negligible.

The crucial point is the political acceptability of the risk in the UK Hitherto this has been regarded as unacceptable, and it would be no less now than when previously considered. My advice is that the risk is appreciable and should not be accepted.

S. S.C. M. C. G.W. L. 27th October 1961

[Taken from TNA: PRO AVIA 66/7]

From 1946 to 1964 five Departments of State did the work of the modern Ministry of Defence: the Admiralty, the War Office, the Air Ministry, the Ministry of Aviation and an earlier form of the present Ministry of Defence. These departments merged in 1964, apart from the defence functions of the Ministry of Aviation which were merged into the Ministry of Defence in 1971.

The main purpose of the Ministry of Defence in the early 1950s was to co­ordinate the three services. At this point in its history it did not have the powers that it would later have. Duncan Sandys was appointed Minister in 1957 by Macmillan, and was given much extended powers. He is remembered for his 1957 Defence White Paper, which was (unfairly) blamed for the demise of a large part of the aircraft industry. It would be more correct to say that Sandys was the first to articulate changes that were inevitable and probably overdue.

The Ministry of Defence did have considerable influence on policy by means of the extremely powerful DRPC. It was this committee that decided general defence policy needs and hence which projects should proceed. The cancellation of the rocket interceptors was a direct consequence of a change in policy initiated by the DRPC, and the requirement for a ballistic missile originated with the DRPC.

The Treasury

The final arbiter was the Treasury. For a project such as Blue Streak, which could be considered as one of national priority, considerable delays were incurred as a result of Treasury refusal to release funds. The Spadeadam facilities were delayed for some six months as a consequence of Treasury reluctance, as this memo from the Ministry of Defence indicates.

You will remember that in February the Minister of Supply wrote to you in connection with the project to develop a rocket testing site in Spadeadam and emphasised the necessity of settling as quickly as possible the fate of our medium range ballistic missile project. We agreed at the time that nothing should be done about this letter since we had not yet settled the problems raised by the Long Term Defence Review. The Ministry of Supply, however, are now being held up by Treasury refusal to agree any expenditure at Spadeadam until the Financial Secretary has seen your reply to the Minister of Supply’s letter of 15th February [1956].2

Sir Frederick Brundrett, Chief Scientist at the Ministry of Defence and chairman of the DRPC, wrote:

There is no doubt whatever that the political uncertainties stemming originally from the reports of the meeting at Chequers, and particularly the bitter hostility of the Exchequer and the Treasury to the project, have contributed to the difficulties, and in particular, specifically caused the work at Spadeadam to proceed at a speed less than the maximum that would have been possible had money been available.3

Again, an excerpt from a minute to the Minister of Defence in October 1957 reads:

During most of 1956 we were defending the very existence of Blue Streak against savage attacks by the Treasury.4

But amidst the controversy the military case was being made that

the conclusion from these arguments is that of all the weapons under consideration only the ballistic missile looks like having a reasonable chance of remaining comparatively invulnerable by 1970. What is more the firing sites for ballistic missiles will be difficult targets to destroy. It is clear, therefore, that unless we change our present policy of maintaining continuously in being an effective contribution of our own to the strategic deterrent, we must retain in the programme the ballistic missile.5

If, in 1957, Britain intended to maintain its deterrent, then it needed a ballistic missile, and Blue Streak was the only option, whatever the Treasury might have thought. Often delays meant that, in the long run, the whole project cost even more. Then came the financial crisis of 1958, when the entire Government

Treasury team resigned in protest at the size of public spending. £100 million had to be cut from Government expenditure, with the consequence that Macmillan wrote to the Minister of Defence and the Chancellor in December 1958: ‘on Blue Streak we should take all steps to reduce expenditure which can be taken without giving any widespread impression that the approved programme is being abandoned or retarded. … of the order of £1M.’6

It is difficult to see why the Treasury seems to have opposed the project so bitterly: other defence programmes such as the V bombers or the nuclear programme had been equally costly. It is impossible to judge how such economies affected the project, but it would not be unreasonable to say that the first flight of Blue Streak would have been put back by at least six to twelve months by the delays imposed whilst obtaining Treasury clearance. The point was also made more than once by Sandys that such economies would mean that as a consequence of the delays, the system would be late in service, and its useful service life concomitantly reduced.

As mentioned, the original Operational Requirement in July 1951 did not specify a jet engine; the aircraft was to be purely rocket propelled. A meeting of the OR Committee at this time said that ‘it would be a very local defence weapon’ and so ‘The possibility of fitting a small turbine to assist the landing was then discussed but ruled out on the score of weight’. The armament was to be a battery of 2-inch air-to-air rockets. As an indication of the number of aircraft firms that there were at that time, tenders were invited from Bristol, de Havilland, Fairey, AVRoe, and Short Brothers. Copies for information were sent to Armstrong Whitworth, Blackburn, Boulton Paul, English Electric, Gloster, Percival, Saunders Roe, Supermarine, Westland, Folland, Handley Page and Scottish Aviation!

In the minutes of the F.124 tender Design Conference in July 1952, it was announced that ‘General agreement was reached that only the Saunders Roe, AVRoe and Bristol A design remained in the competition..and that ‘Saunders Roe had submitted very good designs on two previous occasions and he felt that their design team were so good that it would be a mistake for it to be disbanded as would be the case unless the firm received a contract soon.’

There are two curious points about this: the fact that it had taken a year to evaluate the designs, and the comment on the Saunders Roe design team: contracts were often awarded for seemingly obscure reasons. The recommendation was made that three prototypes be ordered each from Avro and from Saunders Roe.

However, the huge increase in the defence budget in 1950 could not be sustained, and economy again became the watchword. This meant that three prototypes could not be afforded; despite RAF preference for the AVRoe design, the Ministry of Supply decided to press on with the Saunders Roe design, but with only two prototypes.

But there is an interesting comment from the OR committee sometime later, in June 1953:

… the changes in requirement that have been brought in from time to time have moved the design some way from the basic conception of a simple rocket aircraft – and there is some danger, in my opinion, that the final weapon will be less effective than it might be.

Indeed, in a sense this remark could be said to be the essence of the whole story.

However, work progressed rapidly with the SR53: in October 1952 there was a structures meeting between Saunders Roe and the RAE, and a preliminary mock up meeting in Cowes in September 1953.

The final delay in the completion of the first aircraft, XD 145, was delivery of the Spectre I motor: this could not be delivered to Cowes before mid-December 1955. The motor had earlier been installed in Canberra for flight trials. By mid- June 1956 the aircraft was completed, then dissembled for transport to the Aero­plane and Armament Establishment at Boscombe Down. Here it was put together again, and the first rocket engine firing was on 16 January 1957. The first flight took place on 16 May. The second aircraft, XD 151, was first flown on 18 December 1957.

The SR53 was intended to be a lead in for the P177, and the cancellation of the P177 meant that it had lost its purpose. However, it was felt that in many ways that the SR53 was a unique aircraft that could be used for aerodynamic research, rather as the X planes in America. Accordingly, proposals were put forward for enhancing the performance2. It was estimated that the Spectre 1 rocket motor in its then state of 7,000 lb thrust, and S. I. of 190s gave a maximum velocity of Mach 1.8 at 60,000 ft and a maximum height of 76,000 ft. Thus a meeting in May gave some options for further development:

(i) Spectre 5 engine 95,000 ft or M1.8;

(ii) Twin Spectre 125,000 ft or M2.3;

(iii) Spectre 5 and airlaunch at 40,000 ft and M0.8 gives 115,000 ft or M2.9.

The Spectre 5 was an improved version of the rocket motor; the Twin Spectre, as its name suggests, stacked two such motors together.

Figure 31 shows various scenarios for improving the performance of the SR53, and the results that might be obtained.3 It must be said, however, that some parts of this scenario do look a little optimistic. A further problem was that the SR53 as designed was not that well suited for the task, and most of this kind of research had already been done by 1958. As it stood, there were constraints on the airframe, being all aluminium. Kinetic heating meant that certain key parts of the airframe would have to be replaced by stainless steel, and work was done on this by the design team at Osborne House on the Isle of Wight.

Several scenarios were sketched out: with no armament, more fuel could be carried. The jet engine could be removed, and with a more powerful rocket engine and still more fuel, the flight envelope could be extended further. Also suggested was the use of solid fuel Mayfly rockets to assist take-off, and, in the piece de resistance, air launching from a Valiant was proposed. All this would have made XD154 Britain’s answer to the X-15! The Valiant could take the aircraft up to 40,000 ft at a speed of Mach 0.8. Unlike the American X-15, which was underslung, the proposal was to mount the SR53 on top of the Valiant.

In the meantime, flight trials went ahead with XD145 flying supersonic for the first time at around 45,000 ft on its 31st flight, in May 1958. But disaster overtook the programme in June when XD151 crashed during an aborted take-off on its 12th flight. A long and thorough investigation followed. Here is an excerpt from the report4.

TRUE SPIKED – FT./SEC.

Figure 31. The SR53 as a research aircraft – although some of the ideas do seem on the optimistic side for such an aircraft.

The aircraft taxied out at 1200, and the Spectre was started at 1203. Approximately 5 seconds elapsed before the engine went ‘hot’ but this is understood to be normal. The aircraft lined up on the runway and after cockpit checks were completed, and 10° flap selected the aircraft commenced to take off. The aircraft accelerated normally and the nose wheel was raised. About 30 seconds after the pilot had reported ‘hot’, he was heard to call ‘Panic Stations’ and then a moment later, ‘Come and get me will you’. The anti-spin parachute was seen to stream, but the aircraft ran off the end of the runway. Upon impact with a runway marker light pole, a chain fence with concrete posts and finally a large marker light the aircraft broke up and caught fire. The pilot was killed.

An analysis of the film shows that the take-off was abandoned at a very critical stage when the aircraft was half way down the runway and on the point of becoming airborne. The rocket is shown to have ceased to run hot i. e. no flame, at this point. It could not be determined whether or not the rocket was deliberately throttled back by the pilot. There is no sign of the airbrakes having been opened and the aircraft left the runway at an estimated speed of about 145 knots.

The aircraft was on its take-off run, just becoming airborne, when the rocket motor abruptly cut. Whether the pilot took this action was never established, like so many other details of the accident. The aircraft braked hard, but overran the runway. It might still have survived but for a wing catching an obstruction, a runway lamp post. As the aircraft disintegrated, the rocket fuel ignited in a fierce conflagration. No cause for the accident was ever established, and there was no evidence of pilot error. Saunders Roe’s chief test pilot, John Booth, was killed in the accident.

With the investigation producing no clear result, the flight test programme continued, and XD145 made a total of 56 flights, or 22 hours flying time. Peter Lamb, Booth’s successor, described the SR53 as ‘an extremely docile and exceedingly pleasant aircraft to fly’, which, given the kick the rocket engine must have produced, says a lot about the aircraft. It reached a maximum speed of Mach 1.33, not an exceptional speed, altitudes of up to 55,000 ft, but certainly lived up to expectations with a climb rate of 29,000 ft per minute.

By the time the Ministry had decided to go ahead with the possible research project, Saunders Roe had been taken over by Westland. Westland’s policy was to drop fixed wing aircraft development to concentrate on helicopters (and Saunders Roe would later become, for a time, the British National Hovercraft Company). Saunders Roe’s Chief Designer, Maurice Brennan, responsible for all the fixed wing designs, had moved to Hawker Siddeley. The Ministry talked to Hawker Siddeley, but concluded that

… it was not clear for some time whether Westland would be willing to take on this work using the existing Saunders Roe team for the purpose, but they eventually decided to concentrate their activities on helicopter work and decline all fixed wing business. We had no alternative but reluctantly to accept their decision. However, Saunders Roe’s Chief Designer had by this time joined Hawker Siddeley and asked the latter to consider taking the job on. Having examined the matter with them, we reached the conclusion that we could not obtain by this means the programme of work that we wanted within the amount we had set aside for it.

The programme was finally closed in July 1960.

XD154 was set aside at RPE Westcott, and fortunately has been preserved. It is now in the Aerospace Museum at Cosford, with many other famous prototypes including the TSR 2 and Bristol 188.